RFCC Process with Maximized Diesel Yields

ABSTRACT

The present invention relates to a RFCC process. More specifically, the present invention relates to a RFCC process with maximized diesel yield which includes catalytically reacting a catalytic cracking catalyst in which zeolite has been selectively removed, with a petroleum feedstock in a reaction zone of a fluidized bed catalytic cracking unit to thereby obtain a product stream, an unreacted petroleum feedstock and a mixture of the used catalysts, and separating and collecting the product stream from the used catalyst and the unreacted petroleum feedstock.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to Korean Patent Application No.10-2014-0062082 filed May 23, 2014, the disclosure of which is herebyincorporated in its entirety by reference.

TECHNICAL FIELD

The present invention relates to a. RFCC process. More specifically, thepresent invention relates to a RFCC process with maximized diesel, yieldwhich comprises catalytically reacting catalytic cracking catalyst inwhich zeolite has been selectively removed, with a petroleum feedstockin a reaction zone of a fluidized bed catalytic cracking unit to therebyobtain a product stream, an unreacted petroleum feedstock and a mixtureof the used catalysts, and separating and collecting the product streamfrom the used catalyst and the unreacted petroleum feedstock.

BACKGROUND ART

The RFCC process is a process for producing LPG, gasoline, diesel,naphtha and the like by further conducting a catalytic cracking reactionon a heavy residual oil that remains after the fractionation of a crudeoil. According to the RFCC process, LPG, gasoline, diesel and the likeare reproduced by re-cracking the heavy residual oil which itself doesnot contain fuel. This is referred to as a ground oilfield and appliedto an important advanced equipment of refinery companies.

Products which can be obtained through the RFCC process, include varioussubstances based on the boiling point, such as LPG, gasoline and diesel,but the main target product to date is gasoline. In the current RFCCprocess, the yield of gasoline is approximately 50% by weight. Further,considering the MTBE and alkylate resulting from the 04 product obtainedin the RFCC process, the yield of gasoline is in reality more than 60%by weight.

However, as the demand for gasoline is decreasing and shale-gas basedgasoline alternative energy sources are developed, gasoline prices arefalling continuously, and this trend is expected to be more extreme inthe future.

In this regard, there is a need to change a target product of the RFCCprocess to substances other than gasoline. The substance which can bethe most practical alternative can be seen as diesel.

The RFCC process includes various steps. However, considering only thecracking reaction step, it can be seen that the RFCC process consistslargely of a reaction step in the reactor and a regeneration step in theregenerator. The RFCC catalyst and the petroleum feedstock are reactedin the rising tube of the reactor and so the cracking reaction takesplace under the conditions of 532° C. The products produced from thecracking reaction are discharged to the upper part of the reactor. Thecatalyst deactivated by a coke produced during the cracking reactionregenerates the catalyst activity while removing the coke by air burningin the regenerator. The regenerated catalyst is again moved into thereactor to conduct the cracking reaction.

In theory, the catalyst must be completely regenerated during the aboveprocess, but in practice, the catalyst is gradually deactivated. Thereason is because a high temperature steam is injected for the smoothstirring and heat control of the catalyst and the petroleum feedstock inthe reactor section where the reactions occur, and so the zeolite in theRFCC catalyst is dealuminated by the above injected steam and itsstructure collapses.

Also, a small amount or vanadium present in the heavy residual oil formsan eutectic mixture with an aluminium or an alkali metal of zeolite inthe course of removing the coke to induce the structural collapse, thusdeactivating the catalyst.

Due to these problems, in order to maintain gasoline yield a constantlevel, a process catalyst corresponding to about 3-5% by weight of thecatalyst present during the RFCC process is withdrawn, and a freshcatalyst is introduced as required, thus maintaining the gasoline yield.At this time, the catalyst withdrawn from the process is collectivelyreferred to as E-cat. (Equilibrium catalyst) and is considered to be arepresentative catalyst that shows the actual activity of the RFCCprocess. For these reasons, the evaluation of the RFCC catalyst is madeon the catalyst optionally deactivated as in E-cat., rather than on thefresh catalyst.

The E-cat. thus withdrawn has been mainly utilized as a raw material formanufacturing building materials in the past, but as environmentalregulations became more strict, was classified as industrial waste andso the treatment thereof is not easy. Further, there are problems inthat it is undesirable from the viewpoint of environmental protection.

DISCLOSURE OF INVENTION Technical Problem

In view of the above described problems and recent changes in demand,the present invention provides a process with maximized diesel yield bymodifying the conventional E-cat. discarded from the RFCC process andutilizing it in the RFCC process. Specifically, the present inventionprovides a RFCC process with maximized diesel yield which comprisescatalytically reacting a catalytic cracking catalyst in which zeolitehas been selectively removed, with a petroleum feedstock in a reactionzone of a fluidized bed catalytic cracking unit to thereby obtain aproduct stream, an unreacted petroleum feedstock and a mixture of theused catalysts, and separating and collecting the product stream fromthe used catalyst and the unreacted petroleum feedstock.

However, the technical problem to be solved by ale present invention isnot limited to the above, and they problems that are not mentionedherein will be clearly understood by those skilled in the art from thefollowing description.

Technical Solution to the Problem

According to one embodiment of the present invention, a RFCC processwith maximized diesel yield, which comprises catalytically reacting acatalytic cracking catalyst in which zeolite has been selectivelyremoved, with a petroleum feedstock in a reaction zone of a fluidizedbed catalytic cracking unit to thereby obtain a product stream, anunreacted petroleum feedstock and a mixture of the used catalysts, andseparating and collecting the product stream from the used catalyst andthe unreacted petroleum feedstock, is provided.

Advantageous Effects

According to the RFCC process with maximized diesel yield in accordancewith the present invention, since the modified E-cat. is used, thefollow ng effects are available in terms of the catalyst.

First, the pore structure of the RFCC catalyst matrix for pre-crackingcan be used without change.

Second, through the collapse of the zeolite structure, the pores in themesopore or macropore area are well-developed and the activity of thecracking increases.

Third, it is possible to use as a support for metals such as nickel orcobalt to maintain the coke level and so the present RFCC process can beapplied to a traditional RFCC process without change.

Moreover, the RFCC process according to the present invention has thefollowing effects.

First, since the modified E-cat. is used, the diesel yield can bemaximized.

Second, since the E-cat. discarded from a traditional RFCC process isused, the cost of purchasing the catalyst is reduced and economicefficiency is excellent.

Third, the present RFCC process can increase the yield of H₂ in thecourse of producing a coke in the process and so an additional economicbenefit can be expected.

BEST MODE

Hereinafter, the present invention is described in detail by way ofembodiments of the invention such that it can be easily performed bythose having ordinary skill in the art to which this invention belongs.The present invention may be embodied in several different forms, butshould not be construed to be limited to the embodiments set forthherein.

Now, the present invention will, be described in detail.

The RFCC process of the present invention comprises catalyticallyreacting a catalytic cracking catalyst in which zeolite has beenselectively removed, with a petroleum feedstock in a reaction zone of afluidized bed catalytic cracking unit to thereby obtain a productstream, an unreacted petroleum feedstock and a mixture of the usedcatalysts, and separating and collecting the product stream from theused catalyst and the unreacted petroleum feedstock.

First, the cracking catalyst in which zeolite has been selectivelyremoved is catalytically reacted with the petroleum feedstock in areaction zone of a fluidized bed catalytic cracking unit to therebyobtain a product stream, an unreacted petroleum feedstock and a mixtureof the used catalysts.

In the present invention, the catalytic cracking catalyst in whichzeolite has been selectively removed is in a form wherein the E-cat.generated in the conventional RFCC process is modified.

That is, the catalytic cracking catalyst used in the RFCC process of thepresent invention is in a form wherein zeolite in the E-cat. generatedin the conventional RFCC process has been selectively removed. The poreswith a diameter greater than 20 Å make up more than 80% by volume of thetotal pore count of the catalyst. The ratio (Z/M) of the specificsurface area of zeolite and the specific surface area of the matrix maybe 0.2 or less.

It can be seen that zeolite is not sufficiently selectively removeduntil pores with a diameter greater than 20 Å make up more than 80% byvolume of the total pore count of the catalyst. In this case, the yieldof diesel in the cracking reaction would be maximized.

The catalytic cracking catalyst in which zeolite has been selectivelyremoved can be prepared by subjecting to steam treatment under hot waterconditions of greater than 20 bar and greater than 250° C.

The ratio of zeolite present in the catalytic cracking catalyst can becontrolled according to the steam treatment condition. The zeolite canbe effectively selectively removed under hot water conditions of greaterthan 20 bar and greater than 250° C. Under the above conditions, thecontent of zeolite in the catalyst is controlled to be less than 20% byweight. A temperature condition ranging from 250 to 400° C. is morepreferable.

The catalytic cracking catalyst in which zeolite has been selectivelyremoved after the steam treatment can be simply dried without a separatefiring process.

In the present invention, the catalytic cracking catalyst in whichzeolite has been selectively removed can further comprise one or moreselected from the group consisting of nickel and cobalt.

The coke produced in the catalystic cracking reaction plays a veryimportant role in maintaining the overall heat balance of the RFCCprocess. Accordingly, in the case of using a catalytic cracking catalystin which nick or covalt is further introduced, the coke level of theRFCC process can be appropriately maintained, thus maximizing the yieldof diesel.

In this case, the metal content of nickel and cobalt in the crackingcatalyst which said zeolite has been selectively removed can bedetermined from the viewpoint of maintaining an appropriate coke level.In other words, depending on the properties of the petroleum feedstocksuch as the content of API, naphthene content, and the catalyticproperties such as a specific surface area of the matrix and poredistribution, the coke level of the catalytic cracking catalyst in whichzeolite has been selectively removed as described above can vary.Accordingly, the content of nickel and cobalt can be appropriatelycontrolled by those skilled in the art.

Since the RFCC process of the present invention uses the catalyst inwhich zeolite has been selectively removed, the selectivity of dieselcan be very high, but it is likely that the yield of convension itselfis low. Two methods can be applied to compensate for this. One isincreasing the amount catalyst compared to the raw material, and theother one is raising the reaction temperature. The former is a method toinduce the cracking reaction using a relatively large amount of catalystcompared to the same raw material, and the latter is a method toincrease the cracking reaction rate. In the latter case, the presentinvention has no costs associated with the catalyst itself, and can veryeffectively increase the yield of diesel by a simple operation thatraises only the temperature by the addition of water for the steamtreatment. The temperature in the reaction zone of the fluidized bedcatalytic cracking unit for maximizing the diesel yield rangespreferably from 503 to 593° C.

When the catalytic cracking catalyst in which zeolite has beenselectively removed is catalytically reacted with a petroleum feedstockin a reaction zone of a fluidized be catalytic cracking unit, a productstream, an unreacted petroleum feedstock and a mixture of the usedcatalysts are obtained.

The above-described product stream is separated and collected from theused catalyst and the unreacted petroleum feedstock to obtain a desiredcarbon compound comprising a diesel.

According lode RFCC process oldie present invention, the selectivity ofdiesel is increased by using the catalytic cracking catalyst asdescribed above, the selectivity of zeolite is increased and so thediesel yield in the product stream is increased.

Example 1 (1) Preparation of Catalyst

800 g of E-Cat. generated in the RFCC process was introduced in 2 Lautoclave in which 300 g of water was introduced and sealed. Withstirring at 300 rpm, the reaction was then heated up to 350° C. at arate of 20 bar, 10° C./min and then maintained for 6 hours when itbecame 350° C. After the reaction was completed, water was removed viafiltering, and then dried in 100° C. oven. In order to determine thephysical properties of the dried catalytic cracking catalyst in whichzeolite has been selectively removed, the catalyst was subjected to BET,XRD and XRF analysis, to confirm whether the zeolite remained in thecatalyst. The content of zeolite in the catalyst was 1.8% by weight, andpores with a diameter of less than 20 Å were 18% by volume of the entirecatalyst pore count. The ratio (Z/M) of a specific surface area ofzeolite and a specific surface area of matrix was 0.1, based on thespecific surface area. The analysis was conducted five times in thismanner and ensured the catalytic cracking catalyst in which zeolite hasbeen selectively removed.

(2) Deactivation of Catalyst

In order to evaluate the RFCC catalytic activity of the catalyticcracking catalyst in which zeolite has been selectively removed,produced in the above (1), the catalyst was deactivated under theoperating conditions of the process. A fresh catalyst of the RFCCprocess was subjected to XRD analysis of D-cat. under various CPSoperation conditions. The results confirmed that the most similarcatalytic activity to E-cat. was given under CPS30 cycle operatingconditions. The cracking catalyst in which zeolite has been selectivelyremoved, produced in the above (1) under CPS30 cycle operatingconditions was deactivated.

More specifically, in 1 kg of the catalytic cracking catalyst in whichzeolite has been selectively removed, produced in the above (1), Ni, Vand Fe were introduced at 3000, 4000, and 3000 ppm, respectively. Ni, Vand Fe were introduced by the method wherein the compound precursors inthe form of naphthenate were dissolved in toluene, supported on theprepared catalyst and dried. By repeating these methods, the catalyticcracking catalyst was produced in a total of 4 kg. 4 kg of the crackingcatalyst in which Ni, V, Fe were introduced in 3000, 4000, and 3000 ppm,respectively, was introduced into the CPS equipment. Water/catalyst wasoperated under 0.04 h−1 conditions, 1 cycle was configured to maintainby 10 minutes each step at 788° C. under the conditions of N₂, air, N₂,5% propylene (N₂ balance). This was driven for 30 cycles, and finallydeactivated catalytic cracking catalyst was produced. The resultingdeactivated cracking catalyst confirmed the catalystic physicalproperties through BET, XRD, XRF analysis.

(3) Application to the RFCC Process

The heavy residual oil as the petroleum feedstock was catalysticallyreacted with the above prepared catalyst in a reaction zone of afluidized bed catalytic cracking unit to thereby obtain a productstream, an unreacted petroleum feedstock and a mixture of the usedcatalysts. The product stream was separated and collected from the usedcatalyst and the unreacted petroleum feedstock.

TABLE 1 Item Unit Analytical value API 60° F. 21.1 Sulfur Wt. % 0.41Nitrogen Mg/kg 1023 MCRT Wt. % 3.77 Asphaltenes Wt. % 0.3 Fe Mg/kg 4.9Ni Mg/kg 3.3 V Mg/kg 3.9 D1160(° C.) IBP 292.9  5% 378.2 10% 399.1 30%458.3 50% 512.5 60% 544.2 Recovery Vol. % 66

The petroleum feedstock was introduced into the reactor under acondition of 500 g/h, and the stream of the reactor was introduced undera condition of 90 g/h. The reactor was operated at a temperature of 573and the regenerator was operated at a temperature of 700° C. The overallreaction pressure was 1.6 kgf/cm² g. After completion of the reaction,the resulting gas product was analyzed by GC-RGA, and the liquid productwas analyzed by GC-simdist. The coke analysis was performed using theCO/CO₂ analyzer. The petroleum feedstock was introduced into the reactorunder condition of 500 g/h, and stream of the reactor was introducedunder condition of 90 g/h. The reactor was operated at a temperature of573° C., and the regenerator was operated at a temperature of 700° C.The overall reaction pressure was 1.6 kgf/cm²g. After completion of thereaction, the resulting gas product was analyzed by GC-RGA, and theliquid products were analyzed by GC-simdist. The coke analysis wasperformed using the CO/CO₂ analyzer.

Example 2 (1) Preparation of Catalyst

The catalyst in which 3% by weight of nickel was introduced was preparedby dissolving nickel naphthenate in toluene and then supporting it onthe catalyst obtained in Example 1.

(2) Deactivation of the Catalyst and Application to the RFCC Process

The catalyst was deactivated under the same conditions as Example 1, andthen operated at the reaction temperature of 558° C. under the same DCRoperation conditions to obtain a desired product.

Example 3 (1) Preparation of Catalyst

The catalyst in which 5% by weight of cobalt was introduced was preparedby dissolving cobalt naphthenate in toluene and then supporting it onthe catalyst obtained in Example 1.

(2) Deactivation of the Catalyst, and Application to the RFCC Process

The catalyst was deactivated under the same conditions as Example 1, andthen operated at a reaction temperature of 562° C. under the same DCRoperation conditions to obtain a desired product.

Comparative Example (1) Catalyst

In order to confirm the physical properties of 800 g of E-Cat. generatedin the RFCC process, the catalyst was subjected to BET, XRD and XRFanalysis and then the presence and content of zeolite in the catalystwere confirmed. The content of zeolite in the catalyst was 20.5% byweight and this was calculated based on the specific surface area of thezeolite surface area. The ratio of a specific surface area of zeoliteand a specific surface area of matrix was 0.4, based on the specificsurface area.

(2) Application to the RFCC Process

The heavy residual oil as the petroleum feedstock was catalyticallyreacted with the above prepared catalyst in a reaction zone of afluidized bed catalytic cracking unit to thereby obtain a productstream, an unreacted petroleum feedstock and a mixture of the usedcatalysts. The product stream was separated and collected from the usedcatalyst and the unreacted petroleum feedstock.

EVALUATION

With respect to the product stream obtained in the RFCC process of theExamples and Comparative Examples, the selectivity and content ofdiesel, gasoline and H₂ were evaluated and the results are shown inTable 2 below.

TABLE 2 Comparative Example Example Example Example 1 2 3 Diesel 16.5928.17 35.54 31.83 Gasoline 48.18 31.19 32.15 34.03 H₂ 0.24 0.27 0.940.61 Gas product 19.34 26.27 14.9 17.09 SLO 7.72 6.21 8.58 8.03 coke7.93 7.89 7.89 7.91

Diesel had the temperature ranging from 200 to 360° C., and gasoline wasdefined as a liquid product of not greater than 200° C. The gas productis a product corresponding to C1-C4, and SLO is an unreacted slurry oil.The comparison was performed by an iso-coke criteria which is anoperation criteria actually available in commercial plants. The iso-cokecomparison was performed at coke yield of 793%.

As can be seen from Table 2, according to the RFCC process of thepresent invention, by using the catalytic cracking catalyst in whichzeolite has been selectively removed, the selectivity and yield ofdiesel were significantly increased and the selectivity and yield ofgasoline were lowered.

Moreover, it could be seen that, by further introducing metals of nickelor cobalt into the catalyst, the yield of H₂ was high.

The foregoing description of the present invention is for purposes ofillustration, and it will be very apparent to one of ordinary skill inthe art that modifications can be easily made in other specific formswithout changing the technical spirit or essential feature of thepresent invention. Therefore, the embodiments described above areintended to be illustrative in all respects and should be understood tonot be limiting.

What is claimed is:
 1. A RFCC process with maximized diesel yield which comprises catalytically reacting a catalytic cracking catalyst in which zeolite has been selectively removed, with a petroleum feedstock in a reaction zone of fluidized bed catalytic cracking unit to thereby obtain a product stream, an unreacted petroleum feedstock and a mixture of the used catalysts, and separating and collecting the product stream from the used catalyst and the unreacted petroleum feedstock.
 2. The RFCC process with maximized diesel yield according to claim 1, wherein the catalytic cracking catalyst in which zeolite has been selectively removed has pores in which those with a diameter greater than 20 Å make up more than 80% by volume of the total probe count of the catalyst, and the ratio (Z/M) of a specific surface area of zeolite and a specific surface area of matrix is 0.2 or less.
 3. The RFCC process with maximized diesel yield according to claim 1, wherein the catalytic cracking catalyst in which zeolite has been selectively removed was subjected to steam treatment under hot water conditions of greater than 20 bar and greater than 250° C. and so the content of zeolite in the catalyst is controlled to less than 20% by weight.
 4. The RFCC process with maximized diesel yield according to claim 1, wherein the catalytic cracking catalyst in which zeolite has been selectively removed further comprises one or more selected from the group consisting of nickel and cobalt.
 5. The RFCC process with maximized diesel yield according to claim 1, wherein the petroleum feedstock is a heavy residual oil which undergoes fractional distillation of the raw oil.
 6. The RFCC process with maximized diesel yield according to claim 1, wherein the temperature in the reaction zone of the fluidized bed catalytic cracking unit ranges from 503 to 593° C. 